Winders are machines that roll lengths of paper, commonly known as paper webs, into rolls. These machines are capable of rolling lengths of web into rolls at high speeds through an automated process. Turret winders are well known in the art. Conventional turret winders comprise a rotating turret assembly which support a plurality of mandrels for rotation about a turret axis. The mandrels travel in a circular path at a fixed distance from the turret axis. The mandrels engage hollow cores upon which a paper web can be wound. Typically, the paper web is unwound from a parent roll in a continuous fashion, and the turret winder rewinds the paper web onto the cores supported on the mandrels to provide individual, relatively small diameter logs. The rolled product log is then cut to designated lengths into the final product. Final products typically created by these machines and processes are toilet tissue rolls, paper toweling rolls, paper rolls, and the like.
The winding technique used in turret winders is known as center winding. A center winding apparatus, for instance, is disclosed in U.S. Pat. Reissue No. 28,353 to Nystrand, which is incorporated herein by reference. In center winding, a mandrel is rotated in order to wind a web into a roll/log, either with or without a core. Typically, the core is mounted on a mandrel that rotates at high speeds at the beginning of a winding cycle and then slows down as the size of the rolled product being wound increases, in order to maintain a constant surface speed, approximately matching web speed. Center winders work well when the web that is being wound has a printed, textured, or slippery surface. Also, typically, center winders are preferable for efficiently producing soft-wound, higher bulk rolled products.
A second type of winding is known in the art as surface winding. A machine that uses the technique of surface winding is disclosed in U.S. Pat. No. 4,583,698. Typically, in surface winding, the web is wound onto the core via contact and friction developed with rotating rollers. A nip is typically formed between two or more co-acting roller systems. In surface winding, the core and the web that is wound around the core are usually driven by rotating rollers that operate at approximately the same speed as the web speed. Surface winding is preferable for efficiently producing hard-wound, lower bulk rolled products.
A problem found in both center and surface winders involves the winder shutting down when a condition such as a core load fault or a web break fault occurs. If a core on a turret winder, for instance, is not properly loaded onto the mandrel, the machine must shut down for the fault to be corrected. Similarly, a web break fault in a surface winder will also result in shutting the machine down. This results in a production loss and the immediate requirement to obtain repair services. The present invention provides a way of eliminating such problems by allowing the machine to continue to produce rolled product even though a fault condition has occurred. Additionally, the invention incorporates the advantages of both center and surface winding to produce rolled products having various characteristics by using either center winding, surface winding, or a combination of center and surface winding.
Another problem with both conventional center and surface winders is that the winders provide limited control over the properties of the resulting rolled product. For instance, with respect to center winders, the only control mechanism for controlling the roll bulk of the finished product is web tension. Thus, center winders can only produce products having a limited range of roll bulk without causing excessive delay or increasing product strength to undesirable levels.
Surface winders are also similarly limited in the ability to control the roll bulk of resulting products. Surface winders, for instance, depend on surface friction to drive the winding roll. Attempts to produce products with a relatively high roll bulk require that the contact pressure between the material being wound and the surface winding device be decreased. Decreasing contact pressure, however, also decreases friction and results in loss of control over the product being formed leading to quality issues and productivity issues associated with log instability in the winding pocket. Surface winders also have problems running at relatively higher speeds when producing products with higher roll bulks.
In view of the above, a need currently exists for a system and process that is capable of producing rolled products having a greater range of roll bulk characteristics. In addition, a need exists for a system and process capable of producing products either having a low roll bulk or a high roll bulk while also producing the products at relatively high speeds and without interruption.
In the prior art, a winder is typically known as an apparatus that performs the very first wind of that web, generally forming what is known as a parent roll. A rewinder, on the other hand, is an apparatus that winds the web from the parent roll onto a roll that is essentially the finished product. It is to be noted, the prior art is not consistent in designating what is and is not a winder or rewinder. For instance, rewinders are sometimes called winders, and winders are sometimes referred to as rewinders.